/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.runners.core.metrics;



import com.bff.gaia.unified.sdk.annotations.Experimental;

import com.bff.gaia.unified.sdk.annotations.Experimental.Kind;

import com.bff.gaia.unified.sdk.annotations.Internal;

import com.bff.gaia.unified.sdk.metrics.Counter;

import com.bff.gaia.unified.sdk.metrics.MetricName;

import com.bff.gaia.unified.sdk.metrics.MetricsContainer;



import java.util.Objects;

import java.util.concurrent.atomic.AtomicLong;



/**

 * Tracks the current value (and delta) for a Counter metric for a specific context and bundle.

 *

 * <p>This class generally shouldn't be used directly. The only exception is within a runner where a

 * counter is being reported for a specific step (rather than the counter in the current context).

 * In that case retrieving the underlying cell and reporting directly to it avoids a step of

 * indirection.

 */

@Experimental(Kind.METRICS)

public class CounterCell implements Counter, MetricCell<Long> {



  private final DirtyState dirty = new DirtyState();

  private final AtomicLong value = new AtomicLong();

  private final MetricName name;



  /**

   * Generally, runners should construct instances using the methods in {@link

   * MetricsContainerImpl}, unless they need to define their own version of {@link

   * MetricsContainer}. These constructors are *only* public so runners can instantiate.

   */

  @Internal

  public CounterCell(MetricName name) {

    this.name = name;

  }



  /**

   * Increment the counter by the given amount.

   *

   * @param n value to increment by. Can be negative to decrement.

   */

  @Override

  public void inc(long n) {

    value.addAndGet(n);

    dirty.afterModification();

  }



  @Override

  public void inc() {

    inc(1);

  }



  @Override

  public void dec() {

    inc(-1);

  }



  @Override

  public void dec(long n) {

    inc(-1 * n);

  }



  @Override

  public DirtyState getDirty() {

    return dirty;

  }



  @Override

  public Long getCumulative() {

    return value.get();

  }



  @Override

  public MetricName getName() {

    return name;

  }



  @Override

  public boolean equals(Object object) {

    if (object instanceof CounterCell) {

      CounterCell counterCell = (CounterCell) object;

      return Objects.equals(dirty, counterCell.dirty)

          && Objects.equals(value.get(), counterCell.value.get())

          && Objects.equals(name, counterCell.name);

    }



    return false;

  }



  @Override

  public int hashCode() {

    return Objects.hash(dirty, value.get(), name);

  }

}